Okamoto T et al. (2005) Serum carcinoembronic antigen as a predictive marker for sensitivity to gefitinib in advanced non-small cell lung cancer. Eur J Cancer 41: 1286–1290

Researchers in Japan have demonstrated that patients with advanced non-small-cell lung cancer (NSCLC) with elevated levels of serum carcinoembryonic antigen (CEA) have increased sensitivity to gefitinib. This research stems from previous studies that have shown that different patient populations have varying sensitivity to this anticancer drug.

The retrospective trial, which included 105 patients with advanced NSCLC, analyzed patients for a variety of pretreatment variables including CEA serum concentration. Patients received oral gefitinib 250 mg/day until disease progression, unacceptable toxicity, or patients' withdrawal.

The results from the study showed that the overall response rate to gefitinib was 27.8% and the median survival 9.3 months. The investigators compared responders with non-responders and found that patients with elevated CEA levels were more likely to be sensitive to gefitinib. They also found that elevated CEA is an independent positive prognostic factor for gefitinib treatment.

The data from the trial are surprising, because elevated CEA is generally considered to be a negative prognostic factor for NSCLC. The data suggest that CEA proteins play an important role in epidermal growth factor receptor signaling. The authors also note that there could be a link between a mutant form of epidermal growth factor receptor, which is more sensitive to gefitinib, and elevated CEA levels. Further clinical and basic work is required to elucidate the relationship between gefitinib sensitivity and the CEA protein.